Delta Keyer Node

The Delta Keyer is an advanced implementation of color difference keying. It combines several systems that work in sequence: the Key tab is the main color difference keyer, Pre-Matte smooths out the screen variations, and the following tabs refine the result.

As the official documentation puts it: "the tabs are arranged in the order you typically use them". Follow that order = a clean workflow.

A single Delta Keyer rarely gets a perfect result on a complex shot. Best practice is to chain several of them (hard core + soft edges) and connect a Clean Plate to the dedicated input.

• Effects Library: Tools > Matte > Delta Keyer
• Quick add: right-click in the Node Editor → Add Tool > Matte > Delta Keyer

• Input (orange) - required. The plate containing the backdrop to key.
• Garbage Matte (gray) - optional. Areas made transparent (rigs, studio edges).
• Solid Matte (white) - optional. Areas forced to full opacity (protecting parts of the subject with colors close to the key).
• Clean Plate (magenta) - optional but highly recommended. The output of a Clean Plate node as an even backing reference.
• Effect Mask (blue) - optional. Limits the keying to an area after processing.

                    ┌→ Clean Plate ─(magenta)┐
MediaIn (plate) ────┤                         ↓
                    └→ Delta Keyer ───────────┤
                           ↓ (extracted alpha)
                     Merge 2D ← Replacement background
                           ↓
                         Saver

6 tabs to go through in order:

1. Key - the color difference master. Picking the screen color.
2. Pre-Matte - smoothing the screen variations before the final key.
3. Matte - refining the alpha (threshold, restore fringe, erode, dilate, blur).
4. Fringe - spill suppression and color corrections on the edges.
5. Tuning - advanced adjustments by tonal range (shadows, midtones, highlights).
6. Mask - integrating the Garbage/Solid Matte into the result.

Background Color

An eyedropper to pick the screen color in the viewer. Drag over a representative area of the backdrop.

Pre-Blur

A light blur applied before the key to reduce the video noise and grain that disturb detection.

Gain

Strength of the computed difference. Raise it for sharper edges, lower it to keep more semi-transparency.

Balance

The proportions between the two other channels (e.g. for green = green vs red+blue). According to the documentation, it determines the proportions of the other two channels by comparing the dominant and secondary channels.

Works like a garbage matte keyer before the main delta keying. It compensates for lighting variations on the screen.

• Soft Range - widens the color tolerance to include the variations.
• Erode - shrinks the detected edges to avoid spilling onto the subject.

Recommended workflow: view the Pre-Matte tab in a viewer while adjusting → goal: get a "flat", even screen.

Fine control over the alpha channel produced. View it in alpha mode while adjusting.

• Threshold (range) - values under the low threshold become black (transparent), values above the high one become white (opaque). In between: semi-transparency.
• Restore Fringe - brings back edges clipped by an overly aggressive threshold.
• Erode / Dilate - shrinks or grows the alpha. Erode to remove halos, Dilate to bring back lost edges.
• Blur - softens the edges for a more natural look.

Removes the spill (green/blue reflections on the subject) and corrects the semi-transparent pixels.

Spill Method

• None - no suppression (for debugging).
• Rare - light.
• Medium - recommended for green screen.
• Well Done - recommended for blue screen.
• Burnt - maximum, for problem shots.

Fringe adjustments

Color corrections on the semi-transparent pixels (hair, smoke). Avoids the green halos that linger after spill suppression.

Advanced adjustments that let you apply the keying differently across the shadows, midtones, highlights of the subject. Example: a subject in black clothes needs a different treatment in the shadows than in the highlights.

It also lets you adjust the strength of the spill suppression per tonal range.

Advanced use - rare for a simple key. Go there if the standard Matte tab is not enough.

The official workflow recommended by the documentation:

1. Key tab: eyedropper on the screen, adjust Gain and Balance for a decent base.
2. Pre-Matte tab: view in Pre-Matte mode, adjust Soft Range and Erode to smooth the variations.
3. Matte tab: view the alpha channel (viewer), adjust Threshold and Restore Fringe to refine.
4. Fringe tab: Spill Method for green (Medium) or blue (Well Done), Fringe adjustments for the edges.
5. Complex shots: chain several Delta Keyers - one for the "hard core" (main subject), one for the soft edges (hair, smoke, motion blur).
6. Separate color correction - do the color grade in a separate branch, not in the Delta Keyer.

• Standard film / TV green screen - the pro choice. Key → Pre-Matte → Matte → Fringe workflow in ~5 min on a decent shot.
• Blue screen - same workflow, Spill Method Well Done instead of Medium.
• Shot with fine hair - chain 2 Delta Keyers: one for the solid subject, a second one optimized for the hair (light Pre-Blur, low Gain, high Restore Fringe). Merge the two alphas.
• Poorly lit screen - Clean Plate upstream + Delta Keyer. A far better result than the Chroma Keyer alone.
• Shot with smoke / motion blur - high Restore Fringe + Medium spill to keep the semi-transparency.
• Subject with green elements - a painted Solid Matte to protect the green areas of the subject (e.g. clothing, makeup).

• Clean Plate = level up - the difference between a decent key and a perfect key is often just adding a Clean Plate on the magenta input.
• View the alpha while in the Matte tab - click the alpha triangle of the viewer to see only the alpha channel. Essential to set Threshold precisely.
• Tab order = adjustment order - don't skip tabs. Key first, then Pre-Matte, then Matte, etc.
• Multiple keyers for hard cases - a single Delta Keyer reaches its limits on smoke, fine hair, reflections. The classic chain: a hard key for the subject + a soft key for the edges.
• Pre-Blur of 1-2 pixels - a very light Pre-Blur dramatically improves key quality on noisy footage (low light, high ISO).
• Spill Method overdose - Burnt can create dark artifacts on the subject. Start with Medium and go up step by step.
• Animated polygon Garbage Matte - remove the non-screen elements (floors, rigs) before keying. Draw a Bezier polygon around the subject that follows its movement.
• For really extreme cases (VFX compositing), Primatte (a separate license in Resolve Studio) remains the industry standard. The Delta Keyer covers 95% of cases.